function GVerify (options) { // 创建一个图形验证码对象，接收options对象为参数
  this.options = { // 默认options参数值
   id: '', // 容器Id
   canvasId: 'verifyCanvas', // canvas的ID
   width: '80', // 默认canvas宽度
   height: '30', // 默认canvas高度
   type: 'number', // 图形验证码默认类型blend:数字字母混合类型、number:纯数字、letter:纯字母
   code: ''
  }
  
  if (Object.prototype.toString.call(options) === '[object Object]') { // 判断传入参数类型
   for (var i in options) { // 根据传入的参数，修改默认参数值
    this.options[i] = options[i]
   }
  } else {
   this.options.id = options
  }
  
  this.options.numArr = '0,1,2,3,4,5,6,7,8,9'.split(',')
  this.options.letterArr = getAllLetter()
  
  this._init()
  this.refresh()
 }
  
 GVerify.prototype = {
  /** 版本号**/
  version: '1.0.0',
  
  /** 初始化方法**/
  _init: function () {
   var con = document.getElementById(this.options.id)
   var canvas = document.createElement('canvas')
   // this.options.width = con.offsetWidth > 0 ? con.offsetWidth : '30'
   // this.options.height = con.offsetHeight > 0 ? con.offsetHeight : '30'
   this.options.width = '100'
   this.options.height = '40'
   canvas.id = this.options.canvasId
   canvas.width = this.options.width
   canvas.height = this.options.height
   canvas.style.cursor = 'pointer'
   canvas.innerHTML = '您的浏览器版本不支持canvas'
   con.appendChild(canvas)
   var parent = this
   canvas.onclick = function () {
    parent.refresh()
   }
  },
  
  /** 生成验证码**/
  refresh: function () {
   var canvas = document.getElementById(this.options.canvasId)
   if (canvas.getContext) {
    var ctx = canvas.getContext('2d')
   }
   ctx.textBaseline = 'middle'
  
   ctx.fillStyle = randomColor(180, 240)
   ctx.fillRect(0, 0, this.options.width, this.options.height)
  
   if (this.options.type === 'blend') { // 判断验证码类型
    var txtArr = this.options.numArr.concat(this.options.letterArr)
   } else if (this.options.type === 'number') {
    var txtArr = this.options.numArr
   } else {
    var txtArr = this.options.letterArr
   }
  
   for (var i = 1; i <= 4; i++) {
    var txt = txtArr[randomNum(0, txtArr.length)]
    this.options.code += txt
    ctx.font = randomNum(this.options.height / 2, this.options.height) + 'px SimHei' // 随机生成字体大小
    ctx.fillStyle = randomColor(50, 160) // 随机生成字体颜色
    ctx.shadowOffsetX = randomNum(-3, 3)
    ctx.shadowOffsetY = randomNum(-3, 3)
    ctx.shadowBlur = randomNum(-3, 3)
    ctx.shadowColor = 'rgba(0, 0, 0, 0.3)'
    var x = this.options.width / 5 * i
    var y = this.options.height / 2
    var deg = randomNum(-30, 30)
    /** 设置旋转角度和坐标原点**/
    ctx.translate(x, y)
    ctx.rotate(deg * Math.PI / 180)
    ctx.fillText(txt, 0, 0)
    /** 恢复旋转角度和坐标原点**/
    ctx.rotate(-deg * Math.PI / 180)
    ctx.translate(-x, -y)
   }
   /** 绘制干扰线**/
   for (var i = 0; i < 4; i++) {
    ctx.strokeStyle = randomColor(40, 180)
    ctx.beginPath()
    ctx.moveTo(randomNum(0, this.options.width), randomNum(0, this.options.height))
    ctx.lineTo(randomNum(0, this.options.width), randomNum(0, this.options.height))
    ctx.stroke()
   }
   /** 绘制干扰点**/
   for (var i = 0; i < this.options.width / 4; i++) {
    ctx.fillStyle = randomColor(0, 255)
    ctx.beginPath()
    ctx.arc(randomNum(0, this.options.width), randomNum(0, this.options.height), 1, 0, 2 * Math.PI)
    ctx.fill()
   }
  },
  
  /** 验证验证码**/
  validate: function (code) {
   var code = code.toLowerCase()
   var v_code = this.options.code.toLowerCase()
   if (code == v_code) {
    return true
   } else {
    return false
   }
  }
 }
 /** 生成字母数组**/
 function getAllLetter () {
  var letterStr = 'a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z'
  return letterStr.split(',')
 }
 /** 生成一个随机数**/
 function randomNum (min, max) {
  return Math.floor(Math.random() * (max - min) + min)
 }
 /** 生成一个随机色**/
 function randomColor (min, max) {
  var r = randomNum(min, max)
  var g = randomNum(min, max)
  var b = randomNum(min, max)
  return 'rgb(' + r + ',' + g + ',' + b + ')'
 }
  
 export {
  GVerify
 }